[TargetLowering][DAGCombine][MSP430] Shift Amount Threshold in DAGCombine (3) (baseline tests)

Summary:
This is baseline tests for D69326

Incorporates a command line flag for the MSP430 and adds a test cases to help showing the effects of applying D69326

More details and motivation for this patch in D69326

Reviewers: spatel, asl, lebedev.ri

Reviewed By: spatel, asl

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69975

2 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/Target/MSP430/MSP430ISelLowering.cpp b/llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
index 1ee5489f197..b6a658f30a8 100644
--- a/llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
+++ b/llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
@@ -37,6 +37,11 @@ using namespace llvm;
 
 #define DEBUG_TYPE "msp430-lower"
 
+static cl::opt<bool>MSP430NoLegalImmediate(
+  "msp430-no-legal-immediate", cl::Hidden,
+  cl::desc("Enable non legal immediates (for testing purposes only)"),
+  cl::init(false));
+
 MSP430TargetLowering::MSP430TargetLowering(const TargetMachine &TM,
                                            const MSP430Subtarget &STI)
     : TargetLowering(TM) {
@@ -357,6 +362,15 @@ SDValue MSP430TargetLowering::LowerOperation(SDValue Op,
 unsigned MSP430TargetLowering::getShiftAmountThreshold(EVT VT) const {
   return 2;
 }
+
+// Implemented to verify test case assertions in
+// tests/codegen/msp430/shift-amount-threshold-b.ll
+bool MSP430TargetLowering::isLegalICmpImmediate(int64_t Immed) const {
+  if (MSP430NoLegalImmediate)
+    return Immed >= -32 && Immed < 32;
+  return TargetLowering::isLegalICmpImmediate(Immed);
+}
+
 //===----------------------------------------------------------------------===//
 //                       MSP430 Inline Assembly Support
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/MSP430/MSP430ISelLowering.h b/llvm/lib/Target/MSP430/MSP430ISelLowering.h
index 9224e5e3d00..64ddbbdf6c8 100644
--- a/llvm/lib/Target/MSP430/MSP430ISelLowering.h
+++ b/llvm/lib/Target/MSP430/MSP430ISelLowering.h
@@ -124,6 +124,7 @@ namespace llvm {
     bool isZExtFree(EVT VT1, EVT VT2) const override;
     bool isZExtFree(SDValue Val, EVT VT2) const override;
 
+    bool isLegalICmpImmediate(int64_t) const override;
     unsigned getShiftAmountThreshold(EVT VT) const override;
 
     MachineBasicBlock *